A 2,3-dihydropyridazine compound represented by the formula (2):
wherein R1, R2 and R3 are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom or atoms, an alkenyl group which may be substituted with a halogen atom or atoms, an alkoxy group which may be substituted with a halogen atom or atoms, an alkylthio group, an alkylsulfenyl group, an alkylsulfonyl group or a dialkylamino group, is useful as an intermediate of pharmaceuticals and pesticides. For example, 3-imino-6-chloro-2,3-dihydropyridazine-2-acetic acid has been known as an intermediate of sulfonylurea herbicides (e.g. U.S. Pat. No. 4,017,212 and U.S. Pat. No. 4,994,571), and as processes for producing it, a process comprising reacting a salt consisting of chloroacetic acid and triethylamine with 3-amino-6-chloropyridazine (e.g. JP patent No. 2,863,857).